[systemd-devel] [PATCH] service: add support for reboot argument when triggered by StartLimitAction=

[Michael Olbrich]

When rebooting with systemctl, an optional argument can be passed to the
reboot system call. This makes it possible the specify the argument in a
service file and use it when the service triggers a restart.
This is useful to distinguish between manual reboots and reboots caused by
failing services.
---
 man/systemd.service.xml               | 13 +++++++++++++
 src/core/dbus-service.c               |  1 +
 src/core/load-fragment-gperf.gperf.m4 |  1 +
 src/core/service.c                    | 23 ++++++++++++++++++++++-
 src/core/service.h                    |  1 +
 5 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/man/systemd.service.xml b/man/systemd.service.xml
index 5b3afb8..a2a1b6b 100644
--- a/man/systemd.service.xml
+++ b/man/systemd.service.xml
@@ -1017,6 +1017,19 @@ ExecStart=/bin/echo $ONE $TWO ${TWO}</programlisting>
                                 <option>none</option>.</para></listitem>
                         </varlistentry>
 
+                        <varlistentry>
+                                <term><varname>RebootArgument=</varname></term>
+                                <listitem><para>Configure the optional
+                                argument for the
+                                <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+                                system call if
+                                <varname>StartLimitAction=</varname>
+                                is a reboot action. This works just
+                                like the optional argument to
+                                <command>systemctl reboot</command>
+                                command.</para></listitem>
+                        </varlistentry>
+
                 </variablelist>
 
                 <para>Check
diff --git a/src/core/dbus-service.c b/src/core/dbus-service.c
index 0451790..45bfecf 100644
--- a/src/core/dbus-service.c
+++ b/src/core/dbus-service.c
@@ -50,6 +50,7 @@ const sd_bus_vtable bus_service_vtable[] = {
         SD_BUS_PROPERTY("StartLimitInterval", "t", bus_property_get_usec, offsetof(Service, start_limit.interval), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("StartLimitBurst", "u", bus_property_get_unsigned, offsetof(Service, start_limit.burst), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("StartLimitAction", "s", property_get_start_limit_action, offsetof(Service, start_limit_action), SD_BUS_VTABLE_PROPERTY_CONST),
+        SD_BUS_PROPERTY("RebootArgument", "s", NULL, offsetof(Service, reboot_arg), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("PermissionsStartOnly", "b", bus_property_get_bool, offsetof(Service, permissions_start_only), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("RootDirectoryStartOnly", "b", bus_property_get_bool, offsetof(Service, root_directory_start_only), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("RemainAfterExit", "b", bus_property_get_bool, offsetof(Service, remain_after_exit), SD_BUS_VTABLE_PROPERTY_CONST),
diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index 55fd3da..defd66e 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -183,6 +183,7 @@ Service.WatchdogSec,             config_parse_sec,                   0,
 Service.StartLimitInterval,      config_parse_sec,                   0,                             offsetof(Service, start_limit.interval)
 Service.StartLimitBurst,         config_parse_unsigned,              0,                             offsetof(Service, start_limit.burst)
 Service.StartLimitAction,        config_parse_start_limit_action,    0,                             offsetof(Service, start_limit_action)
+Service.RebootArgument,          config_parse_string,                0,                             offsetof(Service, reboot_arg)
 Service.Type,                    config_parse_service_type,          0,                             offsetof(Service, type)
 Service.Restart,                 config_parse_service_restart,       0,                             offsetof(Service, restart)
 Service.PermissionsStartOnly,    config_parse_bool,                  0,                             offsetof(Service, permissions_start_only)
diff --git a/src/core/service.c b/src/core/service.c
index 78a2e06..9026dc5 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -24,6 +24,8 @@
 #include <dirent.h>
 #include <unistd.h>
 #include <sys/reboot.h>
+#include <linux/reboot.h>
+#include <sys/syscall.h>
 
 #include "manager.h"
 #include "unit.h"
@@ -2369,6 +2371,18 @@ static int service_start_limit_test(Service *s) {
         if (ratelimit_test(&s->start_limit))
                 return 0;
 
+        if ((s->start_limit_action == SERVICE_START_LIMIT_REBOOT ||
+             s->start_limit_action == SERVICE_START_LIMIT_REBOOT_FORCE) && s->reboot_arg) {
+                int r;
+
+                r = write_string_file(REBOOT_PARAM_FILE, s->reboot_arg);
+                if (r < 0) {
+                        log_error("Failed to write reboot param to "
+                                  REBOOT_PARAM_FILE": %s", strerror(-r));
+                        return r;
+                }
+        }
+
         switch (s->start_limit_action) {
 
         case SERVICE_START_LIMIT_NONE:
@@ -2404,7 +2418,14 @@ static int service_start_limit_test(Service *s) {
                 log_warning_unit(UNIT(s)->id,
                                  "%s start request repeated too quickly, rebooting immediately.", UNIT(s)->id);
                 sync();
-                reboot(RB_AUTOBOOT);
+                if (s->reboot_arg) {
+                        log_info("Rebooting with arg '%s'.", s->reboot_arg);
+                        syscall(SYS_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
+                                LINUX_REBOOT_CMD_RESTART2, s->reboot_arg);
+                } else {
+                        log_info("Rebooting.");
+                        reboot(RB_AUTOBOOT);
+                }
                 break;
 
         default:
diff --git a/src/core/service.h b/src/core/service.h
index 1992926..fd05e9b 100644
--- a/src/core/service.h
+++ b/src/core/service.h
@@ -189,6 +189,7 @@ struct Service {
 
         RateLimit start_limit;
         StartLimitAction start_limit_action;
+        char *reboot_arg;
 
         UnitRef accept_socket;
 
-- 
1.9.1